The FAA created FAR Part 161 in response to the Airport Noise and Capacity Act of 1990 (known as "ANCA"). The Act directed the FAA to create two new regulations that:

established a phaseout (with limited exceptions) of FAR Part 36 Stage 2 civil subsonic turbojet aircraft with maximum gross takeoff weights over 75,000 pounds by January 1, 2000. There is no equivalent phaseout for lighter aircraft, which include most general aviation models

established stringent requirements for airport proprietors to follow prior to adopting new restrictions on operations of Stage 2 or 3 aircraft — this requirement was implemented through adoption of Part 161

Part 161, "Notice and Approval of Airport Noise and Access Restrictions," is formally codified under Title 14 of the U.S. Code of Federal Regulations (14 C.F.R. Part 161), also know as the Federal Aviation Regulations (FAR). It defines complex processes for airports to follow when considering the adoption of noise or access restrictions that directly or indirectly affect the number or hours of Stage 2 or 3 operations.

Airport owners must examine the effects of any proposed restriction within an "airport noise study area." That includes at least all property within the 65 decibel (dB) Day-Night Average Sound Level (DNL) contour, which is equivalent to the 65 dB Community Noise Equivalent Level (CNEL) contour used in California. (These metrics are described in greater detail here.)

Part 161 directs airports to follow FAR Part 150 methodologies for measurement, modeling, and description of noise, and for determining whether land uses are compatible with a given noise exposure level. The FAA states that the Part 150 procedures give airport owners flexibility but also help ensure a uniform national standard for measuring airport noise impacts. Part 150 supplies guidelines regarding noise levels (measured using DNL or CNEL) that are generally considered compatible with specified land uses. LAWA adopted the Part 150 guidelines when conducting the VNY Part 150 study.

The FAA adopted a broad definition of the term "noise or access restriction," to include any restriction – including airport lease provisions – that affects the operation of aircraft and has the effect of controlling noise. A "noise or access restriction" does not include, however, noise abatement operational procedures (such as displaced thresholds, preferential runway systems, noise abatement flight tracks and the like) because they are not expected to limit the total number or hours of aircraft operations.

It also should be noted that Part 161 does not apply to Stage 2 restrictions proposed before October 2, 1990, Stage 3 restrictions that became effective before that date, or to a number of exempted situations. These so–called "grandfathered" conditions are significant at VNY, because in a parallel effort to the Part 161, LAWA pursed a phase out of noisier aircraft that it proposed in June, 1990. This regulation was enacted by City Council in 2010 and is in effect now. The parallel effort LAWA used to enact the regulation is described in greater detail here.

The rules considered at VNY largely involve restrictions on Stage 2 operations, although it is possible that some Stage 3 operations will be affected. Different requirements apply to restrictions affecting Stage 2 and 3 aircraft.

An airport proprietor can restrict Stage 2 operations without FAA approval so long as it analyzes the effects of the proposal and publishes notice of the restriction.

Airport proprietors are required to publish notice of a proposed restriction in a general circulation newspaper and certain parties must be notified directly. The FAA also will publish the notice in the Federal Register. The notice must:

describe the proposed restriction

discuss the specific need for, and purpose of, the restriction

identify the aircraft operators and types of aircraft to be affected

set forth the proposed effective date of the restriction and the method of implementation

analyze the proposed restriction

invite public comment

The most important requirement with respect to Stage 2 restrictions is the preparation of analysis on the costs and benefits of the proposed restriction, that includes:

an analysis of the anticipated or actual costs and benefits of the proposed restriction

a description of alternative restrictions that were considered

a description of the alternative measures considered that do not involve aircraft restrictions

a comparison of the costs and benefits of the restrictive and non-restrictive alternatives

Although it will not review or approve local Stage 2 restrictions, the FAA has indicated its view that the analytical requirements are intended to be similar for Stage 2 or Stage 3 restrictions. The regulations recommend that airport proprietors prepare the same analysis for Stage 2 as for Stage 3 restrictions. A copy of the FAA's Part 161 Stage 2 application format is available by clicking here.

Part 161 imposes more substantial impediments to Stage 3 restrictions. The process has three principal elements:

analysis to justify the restriction and explain its environmental and economic impact

notifying the public and allowing time for comment on the proposed restriction

submission of the restriction for FAA review and approval

Unlike Stage 2 restrictions, an airport must demonstrate that the benefits of a proposed Stage 3 restriction has a reasonable chance to exceed the costs, and must submit evidence to the FAA proving that:

the proposed restriction is reasonable, nonarbitrary, and nondiscriminatory;

the proposed restriction does not create an unreasonabe burden interstate or foreign commerce;

the proposed restriction is not inconsistent with maintaining the safe and efficient use of the navigable airspace;

the proposed restriction does not conflict with a law or regulation of the United States;

an adequate opportunity has been provided for public comment on the restriction; and

the proposed restriction does not create an unreasonable burden on the national aviation system.

The requirement that FAA must review and approve a Stage 3 restriction increases the agency´s role significantly above review of procedural requirements.